Cadillac Repair: 1991 cadillac 4.9 l., negative battery cable, fuel pressure regulator

Question
after engine is warmed up car will not take gas. if you barely give it the gas you can get to go. it has new fuel filter plug, plug wires cap and button. also if you shut in off and restart it it will run fine for a while. help thank you  Calvin wazenegger

Answer
Hi Calvin,

       I would start by seeing what the fuel pressure is with the engine running. Then remove the vacuum hose from the fuel pressure regulator and it should go up. Fuel pressure should be around 34psi and go up at least 5psi with the hose off. Double check the specs to be sure.

      Checking for codes by pressing off and warmer on the climate control for 5 seconds when the problem acts up might show some EE codes on the fuel data panel. Diagnosing the code(s) might fix the problem.

      With the older 4.9L engines fuel injectors could be shorting out especially if the engine idles normal cold but as the engine warms up it idles rougher.

      One other weak spot is where the negative battery cable attaches to the engine. The cable end needs to be cleaned with sandpaper and also the starter bracket to bare metal if there is one. Sand the  engine block and bolt everything back together: engine, cable, bracket and bolt.
If you need a bolt it is M8 X 1.25 X 1"

      Try those things and see where it leads you. Bill